Using the latest stable release of xfce4 in manjaro. If I change Settings > Display Scale from the default 1x to custom 0.9x, the display appears to scale properly, but the mouse cursor becomes extremely pixelated and is almost unrecognizable.
$ inxi -G
Graphics:
Device-1: AMD RV770 [Radeon HD 4850] driver: radeon v: kernel
Display: x11 server: X.org 1.20.10 driver: loaded: radeon
resolution: <missing: xdpyinfo>
OpenGL: renderer: AMD RV770 (DRM 2.50.0 / 4.19.167-1-MANJARO LLVM 11.0.1)
v: 3.3 Mesa 20.3.3
$ uname -r
4.19.167-1-MANJARO